For the 300 trading days from January 11, 2012 to March 22, 2013, the daily closing price of IBM stock (in $) is well modeled by a Normal model with mean $197.92 and standard deviation $7.16. According to this model, what is the probability that on a randomly selected day in this period the stock price closed?
a) Above $205.08?
b) Below $212.24?
c) Between $183.60 and $205.08?
d) Which would be more unusual, a day on which the stock price closed above $206 or below $180?